economical evaluation of single irrigation efficient of rainfed barley under different agronimic managements at on-farm areas

introduction: two of the main challenges in developing countries are food production and trying to get a high income for good nutrition and reduction of poverty. cereals and legumes are the most important crops in the rainfed areas of the country occupying the majority of dry land areas. irrigated production systems had a main role in food production in the past years; but unfortunately, in recent years, with high population and competition of industry and environment with agricultural sectors, getting adequate irrigation water is difficult. the main purpose of this study is to determine the best option of crop agronomic management. rainfed agriculture is important in the world; because this production system establishes %80 of the agriculture area and prepares %70 of the food in the world. in the lorestan province, production area for rainfed barley is 120,000 ha and the amount produced is 120000 ton (approximately 1009 kg per ha). the purposes of this study were to evaluate cost, benefit and profit of rainfed barley production, economical and non-economical substitution of treatments in different agronomic management, study of sale return, cost ratio, determining break-even of price and comparing it with the guaranteed price of barley and estimating the value of water irrigation. materials and methods: this research was carried out by sample farmers (12 farmers) on rainfed barley at the honam selected site in the lorestan province during 2005-07. at on-farm areas of the upper karkheh river basin (krb) three irrigation levels were analyzed (rainfed, single irrigation at planting time and single irrigation at spring time) under two agronomic managements (advanced management (am) and traditional management (tm). data was analyzed by partial budgeting (pb) technique, marginal benefit-cost ratio (mbcr), and economical and non-economical test. for estimation of net benefit the following formula was used: (1) where: n.b: net income (rials/ ha) , b(w) : gross income, c (w) : cost of production, yg: crop yield (kg/ ha), pg : price of crop(rials/kg), ys: straw yield (kg/ ha ps : price of straw (rials/kg), c1: total fixed cost without cost of water and irrigation (rials/ ha), pw: price of water and irrigation (rials/ m3) and w: amount of water and irrigation (m3/ ha). changes of incomes and changes of costs for every treatment in different crop managements were used as follows: (2) (3) where j and j+1 show existence and substitution crop managements. in order to determine the price of irrigation water, total cost including pump and electromotor, semi deep well, power instrument, maps, pipe transport and implementation network, other primary cost and operation cost were used. the analysis period for the instruments (pump and electromotor, maps, implementation network) was 20 years and for the semi deep well was 30 years. in this study, total cost was referred to the present value with %15 discount rate by uniform series formulas. then, the water was used in the farm. the price of water was determined. capital recovery formula is as follows: (4) where: a: annual value of primary investment costs, p: primary investment costs for irrigation system, i: discount rate and n: analysis period. results and discussion: according to the results, the price of water and irrigation at the research region based on its components and under 15% and 25% interest rates were obtained to be 213 and 338.1 rials per cubic meters, respectively. the barley grain yield and its net benefit under advanced management were more than that obtained under traditional management. in traditional management, the mean barley grain yield for treatments including rainfed, single irrigation (si) - planting and si spring were estimated to be 1572, 2487 and 2670 kgha-1, respectively. the mean profit for rainfed barley production for treatments including rainfed, si-planting and si spring were estimated to be 1270.2, 2314.2 and 2607 (thousand rial.ha-1), respectively. in advanced management, the mean barley grain yield for treatments including rainfed, single irrigation (si) -planting and si spring were estimated to be 2270, 3444 and 2853 kgha-1, respectively. the mean profit for rainfed barley production for treatments including rainfed, si-planting and si spring were estimated to be 1987, 3465.4 and 2519.8 (thousand rial.ha-1), respectively. in the research site, the mean net benefit of rainfed barley under sowing and spring single irrigation and am, increased by about 173% and 98.4%, respectively. conclusion: the results showed that the substitution of am-si planting treatment instead of other treatments was non-economical. on the other hand, in this substitution, decreasing of profit is more than decreasing of cost. finally, at honam site, recommended management include: am + planting si, am + spring si, and rainfed am, respectively.